Image pick-up apparatus

ABSTRACT

Imaging devices and electronic apparatuses incorporating imaging devices or image pick-up elements are provided. An imaging device as disclosed can include a substrate, a first opto-electronic converter having a first area formed in the substrate, and a second opto-electronic converter having a second area formed in the substrate. The first area is larger than the second area. In addition, a light blocking wall can extend from a first surface of the substrate such that at least a portion of the light blocking wall is between the first opto-electronic converter and the second opto-electronic converter.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a national stage application under 35 U.S.C. 371 andclaims the benefit of PCT Application NO. PCT/JP2016/080220 having aninternational filing date of 12 Oct. 2016, which designated the UnitedStates, which PCT application claimed the benefit of Japanese PriorityPatent Application JP 2015-209533 filed on Oct. 26, 2015, thedisclosures of each of which are incorporated herein by reference.

TECHNICAL FIELD

The present technology relates to an image pick-up apparatus. In detail,the present technology relates to an image pick-up apparatus capable ofextending the dynamic range of the image pick-up apparatus.

BACKGROUND ART

There are technologies to extend the dynamic range of image pick-upapparatuses in various methods. For example, a time-division method inwhich images are taken with different sensitivities at different timesso that the images taken at the different times are synthesized isknown.

Additionally, for example, a space-division method in which lightreceiving elements with different sensitivities are provided in an imagepick-up apparatus so that synthesizing a plurality of images taken withthe light receiving elements, respectively, extends the dynamic range ofthe image pick-up apparatus is known (for example, see Patent Literature1 and 2).

Furthermore, for example, an in-pixel memory method in which a memory inwhich the charge overflowing from a photodiode is accumulated isprovided on each pixel in an image pick-up apparatus so that the amountof charge accumulated in an exposure period is increased and theincrease extends the dynamic range of the image pick-up apparatus (forexample, see Patent Literature 3).

CITATION LIST Patent Literature

-   PTL 1: Japanese Patent No. 3071891-   PTL 2: Japanese Patent Application Laid-open No. 2006-253876-   PTL 3: Japanese Patent No. 4317115

SUMMARY OF INVENTION Technical Problem

Increasing the number of divided times in the time division method orincreasing the number of divided spaces in the space division method canextend the dynamic range of an image pick-up apparatus. On the otherhand, however, the increase in number of divided times or divided spacesdegrades the quality of images, for example, due to the occurrence of anartifact or the decrease in resolution.

Additionally, the limit of the memory capacity limits the extension ofthe dynamic range in the in-pixel memory method.

In light of the foregoing, it is desirable to extend the dynamic rangeof an image pick-up apparatus without degrading the quality of images.

Solution to Problem

An image pick-up apparatus according to an aspect of the presenttechnology includes: a pixel array unit, a plurality of unit pixelsbeing arranged in the pixel array unit, the unit pixels including afirst opto-electronic converter, and a second opto-electronic converterhaving a sensitivity lower than a sensitivity of the firstopto-electronic converter, the second opto-electronic converterincluding a light-blocking film formed on a side of the secondopto-electronic converter from which light enters the secondopto-electronic converter.

A lens used to collect light entering the second opto-electronicconverter may not be formed on the second opto-electronic converter.

A light-blocking wall used to prevent light from leaking from anopto-electronic converter into opto-electronic converters next to theopto-electronic converter may be provided between the opto-electronicconverters.

The light-blocking film may have a slit.

The directions in which slits are formed on light-blocking films formedon the adjacent second opto-electronic converters may be different.

The image pick-up apparatus may be a backside-illumination image sensor.

The image pick-up apparatus may be a front-side-illumination imagesensor.

The light-blocking film may be formed on a lower or upper side of awiring layer formed on the second opto-electronic converter.

The light-blocking film may be an amorphous silicon film, a polysiliconfilm, a Ge film, a GaN film, a CdTe film, a GaAs film, an InP film, aCuInSe2 film, Cu2S, a CIGS film, a non-conductive carbon film, a blackresist film, an organic opto-electronic conversion film, or a metalfilm.

In the image pick-up apparatus according to an aspect of the presenttechnology, a unit pixel on a pixel array unit on which a plurality ofunit pixels is arranged includes a first opto-electronic converter and asecond opto-electronic converter having a sensitivity lower than thesensitivity of the first opto-electronic converter. A light-blockingfilm is formed on a side of the second opto-electronic converter fromwhich light enters the second opto-electronic converter.

Advantageous Effects of Invention

According to an aspect of the present technology, the dynamic range ofan image pick-up apparatus can be extended without the degradation ofthe quality of images.

According to embodiments of the present disclosure, an imaging device isprovided. The imaging device can include a substrate, a firstopto-electronic converter having a first area formed in the substrate,and a second opto-electronic converter having a second area formed inthe substrate, wherein the first area is larger than the second area. Inaddition, a trench extends from a first surface of the substrate, suchthat at least a portion of the trench is between the firstopto-electronic converter and the second opto-electronic converter.

In accordance with further embodiments of the present disclosure, animaging device is provided. The imaging device includes a substrate, afirst opto-electronic converter, and a second opto-electronic converter.The second opto-electronic converter has a sensitivity that is lowerthan a sensitivity of the first opto-electronic converter. In addition,a trench extends from a first surface of the substrate such that atleast a portion of the trench is between the first opto-electronicconverter and the second opto-electronic converter.

In accordance with still further embodiments of the present disclosure,an electronic apparatus is provided. The apparatus includes an opticalsystem, an image pick-up element that receives light from the opticalsystem, and a digital signal processor that processes signals receivedfrom the imagine pick-up element. The image pick-up element includes asubstrate, a first opto-electronic converter having a first area formedin the substrate, and a second opto-electronic converter having a secondarea formed in the substrate, wherein the first area is larger than thesecond area. The image pick-up element also includes a light-blockingwall that extends from a first surface of the substrate, wherein atleast a portion of the light-blocking wall is between the firstopto-electronic converter and the second opto-electronic converter.

Note that the effects of the present disclosure are not necessarylimited to the effects described above and can be any one of the effectsdescribed herein.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic system configuration diagram of a CMOS imagesensor using an embodiment of the present technology.

FIG. 2 is a circuit diagram of an exemplary configuration of a unitpixel.

FIG. 3 is an explanatory timing diagram of the operation when theexposure of a unit pixel starts.

FIG. 4 is an explanatory timing diagram of the operation when the unitpixel is read.

FIG. 5 is an explanatory diagram of the property of the amount of lightand the output describing a signal process.

FIG. 6 is an explanatory diagram of a first configuration of a pixel.

FIG. 7 is an explanatory diagram of a second configuration of a pixel.

FIG. 8 is an explanatory diagram of a third configuration of a pixel.

FIG. 9 is an explanatory diagram of a fourth configuration of a pixel.

FIG. 10 is an explanatory diagram of a fifth configuration of a pixel.

FIG. 11 is an explanatory diagram of a sixth configuration of a pixel.

FIG. 12 is an explanatory diagram of a seventh configuration of a pixel.

FIG. 13 is an explanatory diagram of an eighth configuration of a pixel.

FIG. 14 is an explanatory diagram of a ninth configuration of a pixel.

FIG. 15 is an explanatory diagram of a tenth configuration of a pixel.

FIG. 16 is an explanatory diagram of an eleventh configuration of apixel.

FIG. 17 is an explanatory diagram of a twelfth configuration of a pixel.

FIG. 18 is an explanatory diagram of a thirteenth configuration of apixel.

FIG. 19 is an explanatory diagram of a fourteenth configuration of apixel.

FIG. 20 is an explanatory diagram of a fifteenth configuration of apixel.

FIG. 21 is an explanatory diagram of a sixteenth configuration of apixel.

FIG. 22 is an explanatory diagram of an arrangement of pixels havingdifferent sensitivities.

FIGS. 23-B are explanatory diagrams of an arrangement of colors.

FIGS. 24A-C are explanatory diagrams of an arrangement of light-blockingfilms.

FIG. 25 is a diagram of exemplary uses of the image pick-up apparatus.

FIG. 26 is a diagram of a configuration of the image pick-up apparatus.

DESCRIPTION OF EMBODIMENTS

The modes for carrying out the present technology (hereinafter, referredto as embodiments) will be described hereinafter. Note that theembodiments will be described in the following order.

1. Image Pick-up Apparatus Using Present Technology

2. Configuration of Unit Pixel (First to Sixteenth Configurations)

3. Arrangement of First and Second Opto-electronic Converters

4. Exemplary Variations

5. Exemplary uses of Image Pick-up Apparatus

<Image Pick-Up Apparatus Using Present Technology>

FIG. 1 is a schematic system configuration diagram of a CMOS imagesensor that is an image pick-up apparatus using the present technology,for example, a pick-up apparatus using an X-Y address system. In thisexample, the CMOS image sensor is an image sensor applying or partiallyusing a CMOS process.

A CMOS image sensor 10 according to the present exemplary applicationincludes a pixel array unit 11 formed on a semiconductor substrate(chip) (not illustrated), and a peripheral circuit unit integrated withthe pixel array unit 11 on the same semiconductor substrate. Theperipheral circuit unit includes, for example, a vertical drive unit 12,a column processing unit 13, a horizontal drive unit 14, and a systemcontrol unit 15.

The CMOS image sensor 10 further includes a signal processing unit 18,and a data storage unit 19. The signal processing unit 18 and the datastorage unit 19 can be mounted on the same substrate on which the CMOSimage sensor 10 is mounted, or can be placed on a different substratefrom the substrate on which the CMOS image sensor 10 is mounted.Additionally, the process that each of the signal processing unit 18 andthe data storage unit 19 performs can be processed by an external signalprocessing unit provided on a different substrate from the substrate onwhich the CMOS image sensor 10 is mounted, such as a Digital SignalProcessor (DSP) circuit or by software.

In the pixel array unit 11, unit pixels (hereinafter, sometimes referredto merely as “pixels”) are arranged in a row direction and a columndirection, in other words, two-dimensionally arranged in rows andcolumns. The unit pixel includes an opto-electronic converter thatgenerates and accumulates the charge corresponding to the amount oflight that the opto-electronic converter receives. In this example, therow direction is a direction in which pixels are arranged in a pixel row(namely, a horizontal direction), and the column direction is adirection in which pixels are arranged in a pixel column (namely, avertical direction). The concrete configuration of the circuit of theunit pixel and the detailed configuration of the unit pixel will bedescribed below.

In the pixel array unit 11, pixel drive lines 16 are distributed to thepixel rows in the row direction, respectively, and vertical signal lines17 are distributed to pixel columns in the column direction,respectively, in the pixel arrangement in rows and columns. The pixeldrive line 16 transmits a drive signal used for the drive to read asignal from a pixel. FIG. 1 illustrates the pixel drive line 16 as awire. However, the number of wires is not limited to one. First ends ofthe pixel drive lines 16 are connected to output terminals of thevertical drive unit 12 that corresponds to the rows, respectively.

The vertical drive unit 12 includes a shift register or an addressdecoder, and drives the pixels in the pixel array unit 11, for example,simultaneously or row by row. In other words, the vertical drive unit 12cooperates with a system control unit 15 that controls the verticaldrive unit 12 so as to work as a drive unit that controls the operationof each pixel in the pixel array unit 11. The illustration of theconcrete configuration of the vertical drive unit 12 is omitted.However, the vertical drive unit 12 generally includes two scanningsystems; a readout scanning system, and a discharge scanning system.

The readout scanning system sequentially selects and scans the unitpixels in the pixel array unit 11 row by row so as to read signals fromthe unit pixels. The signal read from a unit pixel is an analog signal.The discharge scanning system scans a row in discharge scanning theexposure period earlier than the time when the readout scanning systemreads and scans the row in readout scanning.

The discharge scanning by the discharge scanning system dischargesunnecessary charge from the opto-electronic converters of the unitpixels in the read row. This discharge resets the opto-electronicconverters. Then, the discharge of the unnecessary charge (theresetting) by the discharge scanning system causes so-called electronicshutter operation. In this example, the electronic shutter operation isthe operation in which the charge in the opto-electronic converter isdischarged and exposure is newly started (the accumulation of charge isstarted).

The signal read in a readout operation by the readout scanning systemcorresponds to the amount of light received in and after the readoutoperation or electronic shutter operation immediately before the readoutoperation. Then, the period between the readout timing by the readoutoperation immediately before the current readout operation or thedischarge timing by the electronic shutter operation immediately beforethe current readout operation and the readout timing by the currentreadout operation is the period of exposure of charge in the unit pixel.

A signal is output from each unit pixel in the pixel row selected andscanned by the vertical drive unit 12. The signal is input via eachvertical signal line 17 pixel column by pixel column to the columnprocessing unit 13. The column processing unit 13 processes the signalsoutput via the vertical signal line 17 from the pixels in the selectedrow in the pixel array unit 11 pixel column by pixel column in apredetermined signal process, and temporarily stores the pixel signalsafter the signal process.

Specifically, the column processing unit 13 performs at least a noiseremoval process, for example, a Correlated Double Sampling (CDS)process, or a Double Data Sampling (DDS) process as the signal process.For example, the CDS process removes reset noise or fixed pattern noisespecific to a pixel such as the variations in the threshold of theamplification transistor in the pixel. In addition to the noise removalprocess, the column processing unit 13 can have, for example, ananalog-digital (AD) conversion function so that the column processingunit 13 can convert an analog pixel signal into a digital signal andoutput the digital signal.

The horizontal drive unit 14 includes, for example, a shift register andan address decoder so as to sequentially select a unit circuitcorresponding to the pixel column of the column processing unit 13. Thisselection and scanning by the horizontal drive unit 14 sequentiallyoutputs the pixel signals processed unit circuit by unit circuit in thesignal process by the column processing unit 13.

The system control unit 15 includes, for example, a timing generatorthat generates various timing signals so as to control the drive, forexample, of the vertical drive unit 12, the column processing unit 13,and the horizontal drive unit 14 on the basis of various times generatedby the timing generator.

The signal processing unit 18 includes at least an arithmetic processfunction so as to process the pixel signal output from the columnprocessing unit 13 in various signal processes including the arithmeticprocess. The data storage unit 19 temporarily stores the data necessaryfor a signal process so that the signal processing unit 18 performs thesignal process.

<Configuration of Circuit of Unit Pixel 100>

FIG. 2 is a circuit diagram illustrating the configuration of the unitpixel 100 placed in the pixel array unit 11 in FIG. 1.

The unit pixel 100 includes a first opto-electronic converter 101, afirst transfer gate unit 102, a second opto-electronic converter 103, asecond transfer gate unit 104, a third transfer gate unit 105, a chargeaccumulation unit 106, a reset gate unit 107, a floating diffusion (FD)unit 108, an amplification transistor 109, and a selection transistor110.

Additionally, the unit pixel 100 is wired with a plurality of drivelines as the pixel drive lines 16 illustrated in FIG. 1, for examplepixel row by pixel row. Then, various drive signals TGL, TGS, FCG, RST,and SEL are supplied via the drive lines from the vertical drive unit 12illustrated in FIG. 1. These drive signals are a pulse signal that is inan active state at a high level (for example, the power-supply voltageVDD) and is in a non-active state at a low level (for example, negativepotential) because each transistor of the unit pixel 100 is an NMOStransistor.

The first opto-electronic converter 101 includes, for example, aPN-junction photodiode. The first opto-electronic converter 101generates and accumulates charge corresponding to the amount of lightthat the first opto-electronic converter 101 receives.

The first transfer gate unit 102 is connected between the firstopto-electronic converter 101 and the FD unit 108. The drive signal TGLis applied to the gate electrode of the first transfer gate unit 102.When the drive signal TGL is turned into the active state, the firsttransfer gate unit 102 becomes conductive so that the charge accumulatedin the first opto-electronic converter 101 is transferred to the FD unit108 via the first transfer gate unit 102.

The second opto-electronic converter 103 includes, for example, aPN-junction photodiode, similarly to the first opto-electronic converter101. The second opto-electronic converter 103 generates and accumulatesthe charge corresponding to the amount of light that the secondopto-electronic converter 103 receives.

In comparison between the first opto-electronic converter 101 and thesecond opto-electronic converter 103, the light-receiving surface of thefirst opto-electronic converter 101 has a larger area and a highersensitivity than the area and sensitivity of the second opto-electronicconverter 103. As described above, the unit pixel 100 includes twoopto-electronic converters having different sensitivities. In otherwords, the first opto-electronic converter 101 works as ahigh-sensitivity pixel while the second opto-electronic converter 103works as a low-sensitivity pixel.

The second transfer gate unit 104 is connected between the chargeaccumulation unit 106 and the FD unit 108. The drive signal FCG isapplied to the gate electrode of the second transfer gate unit 104. Whenthe drive signal FCG is turned into the active state, the secondtransfer gate unit 104 becomes conductive so that the potential well ofthe charge accumulation unit 106 and the potential well of the FD unit108 are bound or electrically connected to one another.

The third transfer gate unit 105 is connected between the secondopto-electronic converter 103 and the charge accumulation unit 106. Thedrive signal TGS is applied to the gate electrode of the third transfergate unit 105. When the drive signal TGS is turned into the activestate, the third transfer gate unit 105 becomes conductive so that thecharge accumulated in the second opto-electronic converter 103 istransferred via the third transfer gate unit 105 to the chargeaccumulation unit 106 or a region in which the potential well of thecharge accumulation unit 106 and the potential well of the FD unit 108are bound or electrically connected to one another.

Additionally, the potential well is slightly deeper at the lower part ofthe gate electrode of the third transfer gate unit 105 so as to form anoverflow path through which the charge exceeding the amount of chargewith which the second opto-electronic converter 103 is saturated andoverflowing from the second opto-electronic converter 103 is transferredto the charge accumulation unit 106. Note that the overflow path formedon the lower part of the gate electrode of the third transfer gate unit105 is referred to merely as the overflow path of the third transfergate unit 105.

The charge accumulation unit 106 includes, for example, a capacitor, andis connected between the second transfer gate unit 104 and the thirdtransfer gate unit 105. The counter electrode of the charge accumulationunit 106 is connected between the charge accumulation unit 106 and thepower-supply source VDD that supplies a power-supply voltage VDD. Thecharge accumulation unit 106 accumulates the charge transferred from thesecond opto-electronic converter 103.

The reset gate unit 107 is connected between the power-supply source VDDand the FD unit 108. The drive signal RST is applied to the gateelectrode of the reset gate unit 107. When the drive signal RST isturned into the active state, the reset gate unit 107 becomes conductiveso that the potential of the FD unit 108 is reset into the level of thepower-supply voltage VDD.

The FD unit 108 converts the charge into a voltage signal incharge-voltage conversion and outputs the voltage signal.

The gate electrode of the amplification transistor 109 is connected tothe FD unit 108 while the drain electrode of the amplificationtransistor 109 is connected to the power-supply source VDD. The gateelectrode and the drain electrode work as an input unit of the readoutcircuit that reads the charge retained in the FD unit 108, namely, aso-called source follower circuit. In other words, the source electrodeof the amplification transistor 109 is connected via the selectiontransistor 110 to the vertical signal line 17, and thus theamplification transistor 109 forms the source follower circuit togetherwith the constant current source 111 connected to a first end of thevertical signal line 17.

The selection transistor 110 is connected between the source electrodeof the amplification transistor 109 and the vertical signal line 17. Theselection signal SEL is applied to the gate electrode of the selectiontransistor 110. When the selection signal SEL is turned into the activestate, the selection transistor 110 is conductive so that the unit pixel100 is selected. Thus, the pixel signal is output from the amplificationtransistor 109 via the selection transistor 110 to the vertical signalline 17.

Note that the fact that each drive signal is turned into the activestate is referred to also as “each drive signal is turned on” and thefact that each drive signal is turned into the non-active state isreferred to also as “each drive signal is turned off”. Additionally, thefact that each gate unit or each transistor becomes conductive isreferred to also as “each gate unit or each transistor is turned on” andthe fact that each gate unit or each transistor becomes non-conductiveis referred to also as “each gate unit or each transistor is turnedoff”.

<Operation of Unit Pixel 100>

Next, the operation of the unit pixel 100 will be described withreference to the timing diagrams of FIGS. 3 and 4. First, the operationof the unit pixel 100 at the start of exposure will be described withreference to the timing diagram of FIG. 3. This process is performed,for example, by pixel row or by a plurality of pixel rows in the pixelarray unit 11 in predetermined scanning order. Note that FIG. 3illustrates the timing diagram of the horizontal synchronization signalXHS and the drive signals SEL, RST, TGS, FCG, and TGL.

First, the horizontal synchronization signal XHS is input and theprocess for exposure of the unit pixel 100 is started at a time t1.

Next, the drive signal RST is turned on and the reset gate unit 107 isturned on at a time t2. This resets the potential of the FD unit 108into the level of the power-supply voltage VDD.

Next, the drive signals TGL, FCG, and TGS are turned on and the firsttransfer gate unit 102, the second transfer gate unit 104, and the thirdtransfer gate unit 105 are turned on at a time t3. This binds thepotential well of the charge accumulation unit 106 with the potentialwell of the FD unit 108. Additionally, the charge accumulated in thefirst opto-electronic converter 101 is transferred via the firsttransfer gate unit 102 to the bound region in which the potential wellsare bound. The charge accumulated in the second opto-electronicconverter 103 transferred via the third transfer gate unit 105 to thebound region. Then, the bound region is reset.

Next, the drive signals TGL and TGS are turned off and the firsttransfer gate unit 102 and the third transfer gate unit 105 are turnedoff at a time t4. This starts the accumulation of the charge into thefirst opto-electronic converter 101 and the second opto-electronicconverter 103 and an exposure period starts.

Next, the drive signal RST is turned off and the reset gate unit 107 isturned off at a time t5.

Next, the drive signal FCG is turned off and the second transfer gateunit 104 is turned off at a time t6. This causes the charge accumulationunit 106 to start accumulation of the charge overflowing from the secondopto-electronic converter 103 and transferred through the overflow pathof the third transfer gate unit 105.

Then, the horizontal synchronization signal XHS is input at a time t7.

(Operation of Unit Pixel 100 for Readout)

Next, the operation of the unit pixel 100 for reading a pixel signalwill be described with reference to the timing diagram of FIG. 4. Thisprocess is performed, for example, by pixel row or by a plurality ofpixel rows in the pixel array unit 11 in predetermined scanning orderafter a predetermined period of time has elapsed since the processillustrated FIG. 3 has been performed. Note that FIG. 4 illustrates thetiming diagram of the horizontal synchronization signal XHS and thedrive signals SEL, RST, TGS, FCG, and TGL.

First, the horizontal synchronization signal XHS is input and the periodof readout of the unit pixel 100 starts at a time t21.

The selection signal SEL is turned on and the selection transistor 110is turned on at a time t22. Thus, the unit pixel 100 is selected.

Next, the drive signal RST is turned on and the reset gate unit 107 isturned on at a time t23. Thus, the potential of the FD unit 108 is resetinto the level of the power-supply voltage VDD.

Next, the drive signal RST is turned off and the reset gate unit 107 isturned off at a time t24.

Next, the drive signals FCG and TGS are turned on and the secondtransfer gate unit 104 and the third transfer gate unit 105 are turnedon at a time t25. This binds the potential well of the chargeaccumulation unit 106 and the potential well of the FD unit 108 andtransfers the charge accumulated in the second opto-electronic converter103 to the bound region in which the potential wells are bound. Thus,the charge accumulated in the second opto-electronic converter 103 andthe charge accumulation unit 106 during the exposure period areaccumulated in the bound region.

At the time t25, the readout of the pixel signal is started and theexposure period is completed.

Next, the drive signal TGS is turned off and the third transfer gateunit 105 is turned off at a time t26. This stops the transfer of thecharge from the second opto-electronic converter 103.

Next, the signal SL based on the potential in the region in which thepotential well of the charge accumulation unit 106 and the potentialwell of the FD unit 108 are bound is output via the amplificationtransistor 109 and the selection transistor 110 to the vertical signalline 17 at a time to between the time t26 and the time t27. The signalSL is a signal based on the charge generated in the secondopto-electronic converter 103 and accumulated in the secondopto-electronic converter 103 and the charge accumulation unit 106during the exposure period.

Additionally, the signal SL is a signal based on the potential in thebound region in which the potential well of the charge accumulation unit106 and the potential well of the FD unit 108 are bound when the chargeaccumulated in the second opto-electronic converter 103 and the chargeaccumulation unit 106 during the exposure period is accumulated in thebound region. Thus, the amount of charge converted in charge-voltageconversion when the signal SL is read is the total amount of charge inthe charge accumulation unit 106 and the charge of the FD unit 108.

Note that the signal SL is referred to also as a low-sensitivity datasignal SL hereinafter.

Next, the drive signal RST is turned on and the reset gate unit 107 isturned on at a time t27. This resets the region in which the potentialwell of the charge accumulation unit 106 and the potential well of theFD unit 108 are bound.

Next, the selection signal SEL is turned off and the selectiontransistor 110 is turned off at a time t28. Thus, the unit pixel 100 isnot selected.

Next, the drive signal RST is turned off and the reset gate unit 107 isturned off at a time t29.

Next, the selection signal SEL is turned on and the selection transistor110 is turned on at a time t30. Thus, the unit pixel 100 is selected.

Next, the signal NL based on the potential in the region in which thepotential well of the charge accumulation unit 106 and the potentialwell of the FD unit 108 are bound is output via the amplificationtransistor 109 and the selection transistor 110 to the vertical signalline 17 at a time tb between the time t30 and the time t31. The signalNL is a signal based on the potential in the bound region in which thepotential well of the charge accumulation unit 106 and the potentialwell of the FD unit 108 are bound when the bound region is reset.

Note that the signal NL is referred to also as a low-sensitivity resetsignal NL hereinafter.

Next, the drive signal FCG is turned off and the second transfer gateunit 104 is turned off at a time t31.

Next, the signal NH based on the potential of the FD unit 108 is outputvia the amplification transistor 109 and the selection transistor 110 tothe vertical signal line 17 at a time tc between the time t31 and thetime t32. The signal NH is a signal based on the potential of the FDunit 108 when the FD unit 108 is reset.

Note that the signal NH is referred to also as a high-sensitivity resetsignal NH hereinafter.

Next, the drive signal TGL is turned on and the first transfer gate unit102 is turned on at a time t32. Thus, the charge generated andaccumulated in the first opto-electronic converter 101 during theexposure period is transferred via the first transfer gate unit 102 tothe FD unit 108.

Next, the drive signal TGL is turned off and the first transfer gateunit 102 is turned off at a time t33. This stops the transfer of thecharge from the first opto-electronic converter 101 to the FD unit 108.

Next, the signal SH based on the potential of the FD unit 108 is outputvia the amplification transistor 109 and the selection transistor 110 tothe vertical signal line 17 at a time td between the time t33 and thetime t34. The signal SH is a signal based on the charge generated andaccumulated in the first opto-electronic converter 101 during theexposure period.

Additionally, the signal SH is based on the potential in the FD unit 108when the charge accumulated in the first opto-electronic converter 101during the exposure period is accumulated in the FD unit 108. Thus, theamount of the charge converted in charge-voltage conversion when thesignal SH is read is the amount of charge in the FD unit 108. The amountof charge is smaller than the amount of charge when the low-sensitivitydata signal SL is read at the time ta.

Note that the signal SH is referred to also as a high-sensitivity datasignal SH hereinafter.

Next, the selection signal SEL is turned off and the selectiontransistor 110 is turned off at a time t34. Thus, the unit pixel 100 isnot selected.

Next, the horizontal synchronization signal XHS is input and the readoutperiod in which the pixel signal of the unit pixel 100 is read iscompleted at a time t35.

(Description of Noise Removal Process and Arithmetic Process)

The low-sensitivity data signal SL, the low-sensitivity reset signal NL,the high-sensitivity reset signal NH, and the high-sensitivity datasignal SH are output from the unit pixel 100 to the vertical signal line17 in this order. Then, in signal processing units placed downstream,for example, the column processing unit 13 and signal processing unit 18illustrated in FIG. 1, the low-sensitivity data signal SL, thelow-sensitivity reset signal NL, the high-sensitivity reset signal NH,and the high-sensitivity data signal SH are processed in predeterminednoise removal process and signal process. An exemplary noise removalprocess performed in the column processing unit 13 placed downstream andan exemplary arithmetic process performed in the signal processing unit18 placed downstream will be described hereinafter.

(Noise Removal Process)

First, a noise removal process that the column processing unit 13performs will be described.

(Exemplary Noise Removal Process)

First, an exemplary noise removal process will be described.

The column processing unit 13 generates a low-sensitivity differentialsignal SNL by taking the difference between the low-sensitivity datasignal SL and the low-sensitivity reset signal NL. Thus, thelow-sensitivity differential signal SNL=the low-sensitivity data signalSL−the low-sensitivity reset signal NL holds.

Next, the column processing unit 13 generates a high-sensitivitydifferential signal SNH by taking the difference between thehigh-sensitivity data signal SH and the high-sensitivity reset signalNH. Thus, the high-sensitivity differential signal SNH=thehigh-sensitivity data signal SH−the high-sensitivity reset signal NHholds.

As described above, the low-sensitivity signals SL and NL are processedin a DDS process in which fixed pattern noise specific to a pixel, forexample, the variations in the threshold of the amplification transistorin the pixel is removed but reset noise is not removed. Thehigh-sensitivity signals SH and NH is processed in a CDS process inwhich reset noise and fixed pattern noise specific to a pixel, forexample, the variations in the threshold of the amplification transistorin the pixel are removed.

(Exemplary Arithmetic Process of Pixel Signal)

An exemplary arithmetic process of a pixel signal will be describedhereinafter.

When the low-sensitivity differential signal SNL is in a predeterminedrange, the signal processing unit 18 calculates the proportion of thelow-sensitivity differential signal SNL to the high-sensitivitydifferential signal SNH as gain by pixel, by a plurality of pixels, bycolor, by specific pixel in a shared pixel unit, or evenly in allpixels, and generates a gain table. Then, the signal processing unit 18calculates the product of the low-sensitivity differential signal SNLand the gain table as the correction value of the low-sensitivitydifferential signal SNL.

In this example, the gain is G and the value of the correctedlow-sensitivity differential signal SNL (hereinafter, referred to as acorrected low-sensitivity differential signal) is SNL′. The gain G andthe corrected low-sensitivity differential signal SNL′ can be found withthe following expressions (1) and (2).G=SNH/SNL=(Cfd+Cfc)/Cfd  (1)SNL′=G×SNL  (2)

In this example, Cfd is the value of the capacity of the FD unit 108,and Cfc is the value of the capacity of the charge accumulation unit106. Thus, the gain G is equivalent to the proportion of the capacity ofthe FD unit 108 to the capacity of the charge accumulation unit 106.

FIG. 5 illustrates the relationship between the amount of incident lightand each of the low-sensitivity differential signal SNL, thehigh-sensitivity differential signal SNH, and the correctedlow-sensitivity differential signal SNL′.

Next, the signal processing unit 18 uses a predetermined threshold Vtillustrated in FIG. 5. In terms of a photo-response characteristic, thethreshold Vt is set in a region before the signal processing unit 18 issaturated with the high-sensitivity differential signal SNH and in whichthe photo-response characteristic is linear.

Then, when the high-sensitivity differential signal SNH does not exceedthe predetermined threshold Vt, the signal processing unit 18 outputsthe high-sensitivity differential signal SNH as the pixel signal SN ofthe pixel to be processed. In other words, when SNH<Vt holds, the pixelsignal SN=the high-sensitivity differential signal SNH holds.

On the other hand, when the high-sensitivity differential signal SNHexceeds the predetermined threshold Vt, the signal processing unit 18outputs the corrected low-sensitivity differential signal SNL′ of thelow-sensitivity differential signal SNL as the pixel signal SN of thepixel to be processed. In other words, when Vt≤SNH holds, the pixelsignal SN=the corrected low-sensitivity differential signal SNL′ holds.

By the arithmetic process described above, the signal at a low lightcondition can smoothly be switched to the signal at a high lightcondition.

Additionally, providing the charge accumulation unit 106 in thelow-sensitivity second opto-electronic converter 103 in the CMOS imagesensor 10 can raise the level at which the second opto-electronicconverter 103 is saturated with the low-sensitivity data signal SL.Thus, while the minimum value of the dynamic range is maintained, themaximum value of the dynamic range can be increased. This can extend thedynamic range.

For example, LED flicker sometimes occurs in an in-vehicle image sensor.The LED flicker is a phenomenon in which an image of an objectflickering such as an LED light source is not captured depending on thetime when the object flickers. The LED flicker occurs, for example,because the dynamic range of an image sensor in the past is narrow andit is necessary to adjust the exposure period for each object.

In other words, to deal with objects in various light conditions, animage sensor in the past increases the exposure period for an object ina low light condition and decreases the exposure period for an object ina high light condition. This enables the image sensor in the past todeal with objects in various light conditions even when the dynamicrange of the image sensor is narrow. On the other hand, the image sensorreads the signal at a constant rate regardless of the length of theexposure period. Thus, when the exposure period is set at a unit shorterthan the period in which the signal is read, the light entering theopto-electronic converter outside the exposure period is converted intocharge in opto-electronic conversion and is destroyed without readout.

On the other hand, the CMOS image sensor 10 can extend the dynamic rangeas described above, and can increase the exposure period. This preventsLED flicker from occurring. Additionally, using the CMOS image sensor 10can prevent an artifact occurring when the number of divided times in atime division scheme or the number of divided spaces in a space divisionscheme increases, or can prevent the reduction in resolution.

<Configuration of Unit Pixel>

Next, the configuration of the unit pixel 100 including thehigh-sensitivity first opto-electronic converter 101 and thelow-sensitivity second opto-electronic converter 103 as described abovewill additionally be described. Hereinafter, with reference tocross-sectional views of the unit pixel 100, the configuration of theunit pixel 100 will additionally be described.

(First Configuration of Unit Pixel)

FIG. 6 is a cross-sectional view of the unit pixel 100 when the CMOSimage sensor 10 is a backside-illumination image sensor. The unit pixel100 illustrated in FIG. 6 will be referred to as a unit pixel 100-1hereinafter to indicate that the unit pixel 100 illustrated in FIG. 6has a first configuration.

In the unit pixel 100-1, an on-chip lens 201, a colored filter 202, alight-blocking film 203, and a silicon substrate 204 are layered fromthe upper part of the drawing. The first opto-electronic converter 101and the second opto-electronic converter 103 are formed in the siliconsubstrate 204.

Note that, although not illustrated, for example, a glass cover islayered on the on-chip lens 201, and a wiring layer or a supportingsubstrate is layered under the silicon substrate 204. The partsnecessary for the description will be properly illustrated and describedwhile the illustration and description of the other parts will properlybe omitted hereinafter.

FIG. 6 illustrates the first opto-electronic converter 101-1, the firstopto-electronic converter 101-2, and the second opto-electronicconverter 103. Additionally, the on-chip lenses 201-1 to 201-3 areformed on the three opto-electronic converters, respectively.

The light-blocking film 203 is formed only on the second opto-electronicconverter 103. The light-blocking film 203 has a function to absorb orreflect light. The light-blocking film 203 can be made of a metal filmso that the light-blocking film 203 works as a film that reflects light.The light-blocking film 203 can be a film that absorbs a part of lightand allows a part of the light to pass through the film. Alternatively,the light-blocking film 203 can be an optical absorption film thatabsorbs light.

The light-blocking film 203 is, for example, an amorphous silicon film,a polysilicon film, a germanium (Ge) film, a gallium nitride (GaN) film,a cadmium telluride (CdTe) film, a gallium arsenide (GaAs) film, anindium phosphide (InP) film, a CuInSe2 film, a Cu2S film, a CIGS film, anon-conductive carbon film, a black resist film, or an organicopto-electronic conversion film.

Note that the light-blocking film is formed on the secondopto-electronic converter 103 and the light-blocking film can be made ofthe materials described above also in second to sixteenth configurationsdescribed below. Note that the materials of which the light-blockingfilm is made are examples. The material of which the light-blocking filmis made is not limited to the example materials.

Forming the light-blocking film 203 on the low-sensitivity secondopto-electronic converter 103 as described above causes thelight-blocking film 203 to absorb the light passing through the on-chiplens 201-3 and reduces the light entering the second opto-electronicconverter 103. This further reduces the sensitivity of the secondopto-electronic converter 103. This increases the performance of thesecond opto-electronic converter 103 as the low-sensitivityopto-electronic converter. Thus, the dynamic range can be extended.

(Second Configuration of Unit Pixel)

Next, the second configuration of the unit pixel 100 will be described.FIG. 7 is a cross-sectional view of a unit pixel 100-2 when the CMOSimage sensor 10 is a backside-illumination image sensor, similarly tothe unit pixel 100-1 illustrated in FIG. 6.

In comparison between the unit pixel 100-2 illustrated in FIG. 7 and theunit pixel 100-1 illustrated in FIG. 6, the unit pixel 100-2 has aconfiguration in which the on-chip lens 201-3 formed on the secondopto-electronic converter 103 in the unit pixel 100-1 is removed,differently from the unit pixel 100-1, and the other parts in the unitpixel 100-2 are the same as the parts in the unit pixel 100-1.Hereinafter, the description of the parts similar to the parts of theunit pixel 100-1 will be put with similar reference signs and thedescriptions will properly be omitted. Similarly, the descriptions ofthe other parts will properly be omitted when the other parts aresimilar to the parts of the unit pixel 100-1.

The unit pixel 100-2 has a configuration in which the on-chip lens 201-3is not formed on the second opto-electronic converter 103. Thus, thelight is not collected on the second opto-electronic converter 103 andenters the second opto-electronic converter 103 and the light enteringthe second opto-electronic converter 103 is reduced. This furtherreduces the sensitivity of the second opto-electronic converter 103 andcan extend the dynamic range of the low-sensitivity opto-electronicconverter.

(Third Configuration of Unit Pixel)

Next, the third configuration of the unit pixel 100 will be described.FIG. 8 is a cross-sectional view of a unit pixel 100-3 when the CMOSimage sensor 10 is a backside-illumination image sensor, similarly tothe unit pixel 100-1 illustrated in FIG. 6.

In comparison between the unit pixel 100-3 illustrated in FIG. 8 and theunit pixel 100-1 illustrated in FIG. 6, the unit pixel 100-3 has aconfiguration in which a light-blocking wall 231 is added to theconfiguration of the unit pixel 100-1, differently from the unit pixel100-1, and the other parts of the unit pixel 100-3 are the same as theparts of the unit pixel 100-1.

The light-blocking wall 231 is provided between pixels. In the unitpixel 100-3 illustrated in FIG. 8, the light-blocking walls 231 areprovided between the first opto-electronic converter 101-1 and thesecond opto-electronic converter 103, and between the firstopto-electronic converter 101-2 and the second opto-electronic converter103. As describe above, the light-blocking wall 231 is provided in apixel separation region in which the pixels are separate from eachother. The light-blocking wall 231 can be formed in a trench or grooveand can include one or more insulating films extending from the lightreceiving surface.

The light-blocking walls 231 can be formed in trenches from acombination of a negative fixed charge film and an oxide film. Thecombination can be a combination of a negative fixed charge film, anoxide film, and a metal. Examples of a negative fixed charge filminclude hafnium oxide and tantalum oxide.

The light-blocking wall 231 is used to prevent light leaking from anopto-electronic converter into the opto-electronic converters next tothe opto-electronic converter. Providing the light-blocking wall 231 canreduce, for example, the occurrence of mixture of colors. In addition,the light-blocking wall 231 can prevent light from leaking into a lowsensitivity pixel 103 from other pixels, and can therefore help tomaintain the accuracy of the unit pixel output.

Also in this configuration, forming a light-blocking film 203 on thelow-sensitivity second opto-electronic converter 103 causes thelight-blocking film 203 to absorb the light passing through the on-chiplens 201-3 and reduces the light entering the second opto-electronicconverter 103. This further reduces the sensitivity of the secondopto-electronic converter 103. Thus, the dynamic range can be extended.Providing the light-blocking wall 231 can reduce, for example, theoccurrence of mixture of colors.

(Fourth Configuration of Unit Pixel)

Next, the fourth configuration of the unit pixel 100 will be described.FIG. 9 is a cross-sectional view of a unit pixel 100-4 when the CMOSimage sensor 10 is a backside-illumination image sensor, similarly tothe unit pixel 100-2 illustrated in FIG. 7.

In comparison between the unit pixel 100-4 illustrated in FIG. 9 and theunit pixel 100-2 illustrated in FIG. 7, the unit pixel 100-4 has aconfiguration in which a light-blocking wall 231 is added to theconfiguration of the unit pixel 100-2, differently from the unit pixel100-2, and the other parts, for example, the second opto-electronicconverter 103 without the on-chip lens 201-3 in the unit pixel 100-4 arethe same as the parts of the unit pixel 100-2. Additionally, theconfiguration to which the light-blocking wall 231 is added is the sameas the configuration of the unit pixel 100-3 illustrated in FIG. 8.

Also in this configuration, forming a light-blocking film 203 on thelow-sensitivity second opto-electronic converter 103 causes thelight-blocking film 203 to absorb the light entering the light-blockingfilm 203 and reduces the light entering the second opto-electronicconverter 103. Additionally, an on-chip lens is not formed. This furtherreduces the amount of light entering the second opto-electronicconverter 103. This further reduces the sensitivity of the secondopto-electronic converter 103. Thus, the dynamic range of thelow-sensitivity opto-electronic converter can be extended. Providing thelight-blocking wall 231 can reduce, for example, the occurrence ofmixture of colors.

(Fifth Configuration of Unit Pixel)

Next, the fifth configuration of the unit pixel 100 will be described.FIG. 10 is a cross-sectional view of a unit pixel 100-5 when the CMOSimage sensor 10 is a backside-illumination image sensor, similarly tothe unit pixel 100-1 illustrated in FIG. 6.

In comparison between the unit pixel 100-5 illustrated in FIG. 10 andthe unit pixel 100-1 illustrated in FIG. 6, the unit pixel 100-5 has aconfiguration in which a light-blocking film 251 of the unit pixel 100-5has a different shape from the light-blocking film 203 of the unit pixel100-1, differently from the unit pixel 100-1, and the other parts arethe same as the parts of the unit pixel 100-1. The light-blocking film251 of the unit pixel 100-5 has a slit. The light-blocking film 251 isnot necessarily formed on the slit of the light-blocking film 251.Alternatively, the light-blocking film 251 at the slit can be thinnerthan light-blocking film 251 at parts other than the slit.

Forming a slit on the light-blocking film 251 can cause the secondopto-electronic converter 103 to work as a polarization pixel.

For example, when the second opto-electronic converter 103 is installedon a vehicle and captures an image including the surface of a road, thelight reflected on the surface of the road is a polarized light inparallel to the surface of the road. To capture an image from which sucha polarized light is removed, a slit is formed on the light-blockingfilm 251 in a direction parallel to the surface of the road. This canselectively block the light reflected on the surface of the road and canreceive the light from the other objects.

Forming a slit on the light-blocking film 251 as described above canreduce the light entering the second opto-electronic converter 103 andalso can remove unnecessary light.

When the light-blocking film 251 is used also as a polarizer asdescribed above, the light-blocking film 251 can be made of metal inaddition to the materials described above. Note that using thelight-blocking film as the polarizer can effectively reduce the director indirect light in comparison with using a polarizer made of metal.

Also in this configuration, forming the light-blocking film 251 on thelow-sensitivity second opto-electronic converter 103 reduces the amountof light entering the second opto-electronic converter 103. Thus,lowering the sensitivity can extend the dynamic range. Additionally,forming a slit on the light-blocking film 251 can cause thelight-blocking film 251 to work as a polarizer so as to remove theeffect of unnecessary light such as the reflected light.

(Sixth Configuration of Unit Pixel)

Next, the sixth configuration of the unit pixel 100 will be described.FIG. 11 is a cross-sectional view of a unit pixel 100-6 when the CMOSimage sensor 10 is a backside-illumination image sensor, similarly tothe unit pixel 100-2 illustrated in FIG. 7.

In comparison between the unit pixel 100-6 illustrated in FIG. 11 andthe unit pixel 100-2 illustrated in FIG. 7, the unit pixel 100-6 has aconfiguration in which the light-blocking film 251 of the unit pixel100-6 has a different shape from the light-blocking film 203 of the unitpixel 100-2, differently from the unit pixel 100-2, and the other parts,for example, the second opto-electronic converter 103 without theon-chip lens 201-3 in the unit pixel 100-6 are the same as the parts ofthe unit pixel 100-2. The light-blocking film 251 of the unit pixel100-6 has a slit, similarly to the unit pixel 100-5 illustrated in FIG.10.

Forming a slit on the light-blocking film 251 can reduce the lightentering the second opto-electronic converter 103 and also can removeunnecessary light, similarly to the unit pixel 100-5 (FIG. 10).

Also in this configuration, forming the light-blocking film 251 on thelow-sensitivity second opto-electronic converter 103 reduces the amountof light entering the second opto-electronic converter 103. Thus,lowering the sensitivity can extend the dynamic range. Additionally, anon-chip lens is not formed on the second opto-electronic converter 103.This further reduces the amount of light entering the secondopto-electronic converter 103. Thus, lowering the sensitivity can extendthe dynamic range. Additionally, forming a slit on the light-blockingfilm 251 can cause the light-blocking film 251 to work as a polarizer soas to remove the effect of unnecessary light such as the reflectedlight.

(Seventh Configuration of Unit Pixel)

Next, the seventh configuration of the unit pixel 100 will be described.FIG. 12 is a cross-sectional view of a unit pixel 100-7 when the CMOSimage sensor 10 is a backside-illumination image sensor, similarly tothe unit pixel 100-3 illustrated in FIG. 8.

In comparison between the unit pixel 100-7 illustrated in FIG. 12 andthe unit pixel 100-3 illustrated in FIG. 8, the unit pixel 100-7 has aconfiguration in which the light-blocking film 251 has a slit,differently from the unit pixel 100-3, and the other parts, for example,the light-blocking film 231 provided between pixels in the unit pixel100-7 are the same as the parts of the unit pixel 100-3.

Also in this configuration, forming the light-blocking film 251 on thelow-sensitivity second opto-electronic converter 103 reduces the lightentering the second opto-electronic converter 103. Thus, lowering thesensitivity can extend the dynamic range. Additionally, forming a sliton the light-blocking film 251 can cause the light-blocking film 251 towork as a polarizer so as to remove the effect of unnecessary light suchas the reflected light. Providing the light-blocking wall 231 canreduce, for example, the occurrence of mixture of colors.

(Eighth Configuration of Unit Pixel)

Next, the eighth configuration of the unit pixel 100 will be described.FIG. 13 is a cross-sectional view of a unit pixel 100-8 when the CMOSimage sensor 10 is a backside-illumination image sensor, similarly tothe unit pixel 100-4 illustrated in FIG. 9.

In comparison between the unit pixel 100-8 illustrated in FIG. 13 andthe unit pixel 100-4 illustrated in FIG. 9, the unit pixel 100-8 has aconfiguration in which the light-blocking film 251 has a slit,differently from the unit pixel 100-4, and the other parts, for example,the light-blocking film 231 provided between pixels in the unit pixel100-8 and the second opto-electronic converter 103 without an on-chiplens are the same as the parts of the unit pixel 100-4.

Also in this configuration, forming the light-blocking film 251 on thelow-sensitivity second opto-electronic converter 103 reduces the lightentering the second opto-electronic converter 103. Thus, lowering thesensitivity can extend the dynamic range. Additionally, an on-chip lensis not formed on the second opto-electronic converter 103. This furtherreduces the light entering the second opto-electronic converter 103.Thus, lowering the sensitivity can extend the dynamic range.

Additionally, forming a slit on the light-blocking film 251 can causethe light-blocking film 251 to work as a polarizer so as to remove theeffect of unnecessary light such as the reflected light. Providing thelight-blocking wall 231 can reduce, for example, the occurrence ofmixture of colors.

(Ninth Configuration of Unit Pixel)

FIG. 14 is a cross-sectional view of a unit pixel 100-9 when the CMOSimage sensor 10 is a front-side-illumination image sensor.

In the unit pixel 100-9 illustrated in FIG. 14, an on-chip lens 301, acolored filter 302, a light-blocking film 303, a wiring layer 304, and asilicon substrate 305 are layered from the upper part of the drawing. Afirst opto-electronic converter 101 and a second opto-electronicconverter 103 are formed in the silicon substrate 305.

Note that, although not illustrated in the drawing, for example, a glasscover is layered on the on-chip lens 201. The parts necessary for thedescription will properly be illustrated and additionally describedwhile the illustration and description of the other parts will properlybe omitted.

FIG. 14 illustrates the first opto-electronic converter 101-1, the firstopto-electronic converter 101-2, and the second opto-electronicconverter 103. Additionally, on-chip lenses 301-1 to 301-3 are formed onthe three opto-electronic converters, respectively.

The light-blocking film 303 is formed only on the second opto-electronicconverter 103. The light-blocking film 303 is, for example, an amorphoussilicon film, a polysilicon film, a Ge film, a GaN film, a CdTe film, aGaAs film, an InP film, a CuInSe2 film, Cu2S, a CIGS film, anon-conductive carbon film, a black resist film, or an organicopto-electronic conversion film. Additionally, when the light-blockingfilm 303 has a slit as described below, the light-blocking film 303 canbe made of metal. Note that the materials of which the light-blockingfilm is made are examples and the material of which the light-blockingfilm is made is not limited to the example materials.

Also in the front-side illumination image sensor as described above,forming the light-blocking film 303 on the low-sensitivity secondopto-electronic converter 103 causes the light-blocking film 303 toabsorb the light passing through the on-chip lens 301-3 and reduces thelight entering the second opto-electronic converter 103. This furtherreduces the sensitivity of the second opto-electronic converter 103.Thus, the dynamic range can be extended.

(Tenth Configuration of Unit Pixel)

Next, the tenth configuration of the unit pixel 100 will be described.FIG. 15 is a cross-sectional view of a unit pixel 100-10 when the CMOSimage sensor 10 is a frontside-illumination image sensor, similarly tothe unit pixel 100-9 illustrated in FIG. 14.

In comparison between the unit pixel 100-10 illustrated in FIG. 15 andthe unit pixel 100-9 illustrated in FIG. 14, the unit pixel 100-10 has aconfiguration in which the on-chip lens 301-3 formed on the secondopto-electronic converter 103 in the unit pixel 100-9 is removed,differently from the unit pixel 100-9, and the other parts in the unitpixel 100-10 are the same as the parts in the unit pixel 100-9.

The on-chip lens 301-3 is not formed on the second opto-electronicconverter 103. This causes the light to enter the second opto-electronicconverter 103 without being collected. This reduces the light enteringthe second opto-electronic converter 103. Thus, lowering the sensitivityof the second opto-electronic converter 103 can extend the dynamicrange.

(Eleventh Configuration of Unit Pixel)

Next, the eleventh configuration of the unit pixel 100 will bedescribed. FIG. 16 is a cross-sectional view of a unit pixel 100-11 whenthe CMOS image sensor 10 is a frontside-illumination image sensor,similarly to the unit pixel 100-9 illustrated in FIG. 14.

In comparison between the unit pixel 100-11 illustrated in FIG. 16 andthe unit pixel 100-9 illustrated in FIG. 14, the light-blocking film 303is formed on the upper side of the wiring layer 304 (the side facing theon-chip 301) in the drawing in the unit pixel 100-9 while thelight-blocking film is formed on the lower side of the wiring layer 304(the side facing the silicon substrate 305) in the drawing in the unitpixel 100-11. The other parts in the unit pixel 100-11 are the same asthe parts in the unit pixel 100-9.

With reference to FIG. 14 again, the light-blocking film 303 of the unitpixel 100-9 is formed on the upper side of the wiring layer 304 and inthe colored filter 302. On the other hand, the light-blocking film 331of the unit pixel 100-11 illustrated in FIG. 15 is formed on the lowerside of the wiring layer 304 and in the wiring layer 304 on the siliconsubstrate 305. As described above, the light-blocking film can be formedon the upper or lower side of the wiring layer 304.

As described above, also in a front-side illumination image sensor, thelight-blocking film 303 is formed on the low-sensitivity secondopto-electronic converter 103. This causes the light-blocking film 303to absorb the light passing through the on-chip lens 301-3 and reducesthe light entering the second opto-electronic converter 103. Thisfurther reduces the sensitivity of the second opto-electronic converter103. Thus, the dynamic range can be extended.

(Twelfth Configuration of Unit Pixel)

Next, the twelfth configuration of the unit pixel 100 will be described.FIG. 17 is a cross-sectional view of a unit pixel 100-12 when the CMOSimage sensor 10 is a frontside-illumination image sensor, similarly tothe unit pixel 100-11 illustrated in FIG. 16.

In comparison between the unit pixel 100-12 illustrated in FIG. 17 andthe unit pixel 100-11 illustrated in FIG. 16, the unit pixel 100-12 hasa configuration in which the on-chip lens 301-3 formed on the secondopto-electronic converter 103 in the unit pixel 100-11 is removed,differently from the unit pixel 100-11 and the other parts in the unitpixel 100-12 are the same as the parts in the unit pixel 100-11.

The on-chip lens 301-3 is not formed on the second opto-electronicconverter 103. Thus, light is not collected on the secondopto-electronic converter 103 and enters the second opto-electronicconverter 103. This reduces the light entering the secondopto-electronic converter 103. Thus lowering the sensitivity of thesecond opto-electronic converter 103 and extending the dynamic range.

(Thirteenth Configuration of Unit Pixel)

Next, the thirteenth configuration of the unit pixel 100 will bedescribed. FIG. 18 is a cross-sectional view of a unit pixel 100-13 whenthe CMOS image sensor 10 is a frontside-illumination image sensor,similarly to the unit pixel 100-9 illustrated in FIG. 14.

In comparison between the unit pixel 100-13 illustrated in FIG. 18 andthe unit pixel 100-9 illustrated in FIG. 14, the unit pixel 100-13 has aconfiguration in which the light-blocking film 351 of the unit pixel100-13 has a different shape from the light-blocking film 303 of theunit pixel 100-9, differently from the unit pixel 100-9, and the otherparts of the unit pixel 100-13 are the same as the parts of the unitpixel 100-9. The light-blocking film 351 of the unit pixel 100-13 has aslit shape and formed in the layer of the colored filter 302.

Forming a slit on the light-blocking film 351 can cause thelight-blocking film 351 to work as a polarizer and the secondopto-electronic converter 103 to a polarization pixel.

Also in this configuration, forming the light-blocking film 351 on thelow-sensitivity second opto-electronic converter 103 reduces the lightentering the second opto-electronic converter 103. Thus lowering thesensitivity, which can extend the dynamic range. Additionally, forming aslit on the light-blocking film 351 can cause the light-blocking film351 to work as a polarizer so as to remove the effect of unnecessarylight such as the reflected light.

(Fourteenth Configuration of Unit Pixel)

Next, the fourteenth configuration of the unit pixel 100 will bedescribed. FIG. 19 is a cross-sectional view of a unit pixel 100-14 whenthe CMOS image sensor 10 is a frontside-illumination image sensor,similarly to the unit pixel 100-13 illustrated in FIG. 18.

In comparison between the unit pixel 100-14 illustrated in FIG. 19 andthe unit pixel 100-13 illustrated in FIG. 18, the unit pixel 100-14 hasa configuration in which the on-chip lens 301-3 formed on the secondopto-electronic converter 103 in the unit pixel 100-13 is removed,differently from the unit pixel 100-13 and the other parts in the unitpixel 100-14 are the same as the parts in the unit pixel 100-13. Thelight-blocking film 351 of the unit pixel 100-14 has a slit, and formedin the layer of the colored filter 302.

The on-chip lens 301-3 is not formed on the second opto-electronicconverter 103. Thus, light is not collected on the secondopto-electronic converter 103 and enters the second opto-electronicconverter 103. This reduces the light entering the secondopto-electronic converter 103. This further reduces the sensitivity ofthe second opto-electronic converter 103. Thus, the dynamic range can beextended. Additionally, forming a slit on the light-blocking film 351can cause the light-blocking film 351 to work as a polarizer so as toremove the effect of unnecessary light such as the reflected light.

(Fifteenth Configuration of Unit Pixel)

Next, the fifteenth configuration of the unit pixel 100 will bedescribed. FIG. 20 is a cross-sectional view of a unit pixel 100-15 whenthe CMOS image sensor 10 is a frontside-illumination image sensor,similarly to the unit pixel 100-13 illustrated in FIG. 18.

In comparison between the unit pixel 100-15 illustrated in FIG. 20 andthe unit pixel 100-13 illustrated in FIG. 18, the light-blocking film351 is formed on the upper side of the wiring layer 304 in the drawingin the unit pixel 100-13 while the light-blocking film 381 is formed onthe lower side of the wiring layer 304 in the drawing in the unit pixel100-15. The other parts in the unit pixel 100-15 are the same as theparts in the unit pixel 100-13. In other words, the light-blocking film381 of the unit pixel 100-15 has a slit, and is formed on the lower sideof the wiring layer 304 in the drawing in the unit pixel 100-15.

Also in the front-side illumination image sensor having thisconfiguration, forming the light-blocking film 381 on thelow-sensitivity second opto-electronic converter 103 causes thelight-blocking film 381 to absorb the light passing through the on-chiplens 301-3 and reduces the light entering the second opto-electronicconverter 103. Thus lowering the sensitivity of the secondopto-electronic converter 103, which can extend the dynamic range.Additionally, forming a slit on the light-blocking film 381 can causethe light-blocking film 351 to work as a polarizer so as to remove theeffect of unnecessary light such as the reflected light.

(Sixteenth Configuration of Unit Pixel)

Next, the sixteenth configuration in the unit pixel 100 will bedescribed. FIG. 21 is a cross-sectional view of a unit pixel 100-16 whenthe CMOS image sensor 10 is a frontside-illumination image sensor,similarly to the unit pixel 100-15 illustrated in FIG. 20.

In comparison between the unit pixel 100-16 illustrated in FIG. 21 andthe unit pixel 100-15 illustrated in FIG. 20, the unit pixel 100-16 hasa configuration in which the on-chip lens 301-3 formed on the secondopto-electronic converter 103 in the unit pixel 100-15 is removed,differently from the unit pixel 100-15 and the other parts in the unitpixel 100-16 are the same as the parts in the unit pixel 100-15. Inother words, the light-blocking film 381 of the unit pixel 100-16 has aslit and is formed on the lower side of the wiring layer 304.

The on-chip lens 301-3 is not formed on the second opto-electronicconverter 103. Thus, light is not collected on the secondopto-electronic converter 103 and enters the second opto-electronicconverter 103. This reduces the light entering the secondopto-electronic converter 103. Thus lowering the sensitivity of thesecond opto-electronic converter 103, which can extend the dynamicrange. Additionally, forming a slit on the light-blocking film 381 cancause the light-blocking film 381 to work as a polarizer so as to removethe effect of unnecessary light such as the reflected light.

As described in the first to sixteenth configurations, a film having afunction to absorb light is formed on the low-sensitivity secondopto-electronic converter 103. This reduces the amount of light enteringthe second opto-electronic converter 103. Thus, lowering the sensitivitycan extend the dynamic range.

Additionally, forming a slit on the light-blocking film can cause thelight-blocking film to work as a polarizer. Providing the polarizerremoves the effect of the reflected light (the effect of unnecessarylight) and simultaneously, lowering the sensitivity, which can extendthe dynamic range.

Using the light-blocking film as the polarizer can effectively reducethe direct or indirect light in comparison with using a polarizer madeof metal.

<Arrangement of First and Second Opto-electronic Converters>

The unit pixels 100, each of which includes a first opto-electronicconverter 101 and a second opto-electronic converter 103, are arranged,for example, as illustrated in FIG. 22. In FIG. 22, the unit pixels arereferred to as unit pixels 500. A unit pixel 500 will be described asone of the unit pixels 100-1 to 100-18.

FIG. 22 illustrates an example in which (four by four) 16 unit pixels500-1 to 500-16 are arranged. Each unit pixel 500 includes a firstopto-electronic converter 101 and a second opto-electronic converter103. For example, the unit pixel 500-1 includes a first opto-electronicconverter 101-1 and a second opto-electronic converter 103-1.

The first opto-electronic converter 101 and the second opto-electronicconverter 103 have different sensitivities depending on the size of thelight-receiving surface. In other words, as illustrated in FIG. 22, thelight-receiving surface of the first opto-electronic converter 101 islarger than the light-receiving surface of the second opto-electronicconverter 103.

In the example of FIG. 22, for example, the second opto-electronicconverter 103-1 of a unit pixel is placed on the right and obliquelylower side of the first opto-electronic converter 101-1 of that unitpixel. Although not illustrated, the second opto-electronic converter103-1 can be placed on the right side of the first opto-electronicconverter 101-1. Alternatively, the positional relationship between thesecond opto-electronic converter 103-1 and the first opto-electronicconverter 101-1 can be different from the above. For example, at least aportion of a side of the second opto-electronic converter 103-1 cancoincide with or can be adjacent to a portion of a side of the firstopto-electronic converter 101-1.

In the unit pixel 500, for example, a signal process circuit can beplaced at a part at which the first opto-electronic converter 101 andthe second opto-electronic converter 103 are not arranged. In otherwords, arranging the first opto-electronic converter 101 and secondopto-electronic converter 103 with different light-receiving areascauses an excessive region in the unit pixel 500. However, placing, forexample, a signal process circuit in the excessive region caneffectively use the excessive region.

The colors of the colored filters 202 (302) placed on the unit pixels500 can be arranged, for example, in Bayer arrangement. As illustratedin FIG. 23A, the unit pixel 500-1 can be red (R), the unit pixel 500-2can be green (G), the unit pixel 500-5 can be green (G), and the unitpixel 500-6 can be blue (B).

In the color arrangement described above, with reference to FIGS. 22 and23A again, for example, the first opto-electronic converter 101-1 andthe second opto-electronic converter 103-1 are arranged and the color ofthe colored filter 202 (or 302, hereinafter, the colored filter 202 iscited as an example for the description) is red (R) in the unit pixel500-1. As described above, the first opto-electronic converter 101 andsecond opto-electronic converter 103 arranged in the same unit pixel 500have the color of the same colored filter 202.

As illustrated in FIG. 23B, the colors can be arranged in Bayerarrangement in which four pixels have the same color. In FIG. 23B, theunit pixel 500-1, the unit pixel 500-2, the unit pixel 500-5, and theunit pixel 500-6 are red (R); the unit pixel 500-3, the unit pixel500-4, the unit pixel 500-7, and the unit pixel 500-8 are green (G); theunit pixel 500-9, the unit pixel 500-10, the unit pixel 500-13, and theunit pixel 500-14 are green (G); and the unit pixel 500-11, the unitpixel 500-12, the unit pixel 500-15, and the unit pixel 500-16 are green(G).

In this example, Bayer arrangement is cited as an example of the colorarrangement. However, the present technology can be used for anothercolor arrangement.

A light-blocking film is formed on the second opto-electronic converter103 as described above. The light-blocking film is the light-blockingfilm 203 without a slit illustrated, for example, in FIG. 6(hereinafter, referred to as a solid light-blocking film 203), or thelight-blocking film 251 with a slit illustrated, for example, in FIG.10.

Note that, although the light-blocking film 203 (FIG. 6) will be citedas an example of the solid light-blocking film for the descriptionhereinafter, the description can be applied to the light-blocking film303 (FIG. 14) and the light-blocking film 331 (FIG. 16). Additionally,the light-blocking film 251 (FIG. 10) will be cited as an example of theslit light-blocking film for the description hereinafter. However, thedescription can be applied to the light-blocking film 351 (FIG. 18) andthe light-blocking film 381 (FIG. 20).

When the solid light-blocking films 203 are formed on the unit pixel,the light-blocking film 203 are formed, for example, as illustrated inFIG. 24A. FIG. 24A only illustrates left and upper four pixels among the(four by four) 16 unit pixels 500-1 to 500-16 illustrated in FIG. 22.However, the light-blocking films 203 are similarly formed on the otherpixels.

As illustrated in FIG. 24A, the solid light-blocking films 203 areformed on the second opto-electronic converters 103 in the unit pixels500. For example, the second opto-electronic converter 103 is formed onthe right and lower side of the unit pixel 500-1 illustrated in FIG.24A, and a light-blocking film 203-1 is formed in the region in whichthe second opto-electronic converter 103-1 is formed.

Note that, as illustrated in FIG. 24A, the light-blocking film 203 canbe formed so that the light-blocking film 203 is connected to a well(WELL) in an outer peripheral region of the pixel.

When the slit light-blocking films 251 are formed on the unit pixels,the light-blocking film 251 are formed, for example, as illustrated inFIG. 24B. As illustrated in FIG. 24B, the slit light-blocking films 251are formed on the second opto-electronic converters 103 in the unitpixels 500, respectively.

The slits illustrated in FIG. 24B extend in the lateral direction of thedrawing and all the four pixels have slits extending in the samedirection. As described above, the slits on the light-blocking films 251provided on the second opto-electronic converters 103 can be formed inthe same direction.

The direction in which the slits are arranged on the light-blockingfilms 251 can be varied depending on the pixel. FIG. 24C illustratesthat the light-blocking films 251 are formed on the secondopto-electronic converters 103 in the unit pixels 500, respectively, andthe slits of the light-blocking films 251 with slits are formed indifferent directions depending on the pixel.

The slits on the light-blocking film 251-1 formed on the secondopto-electronic converter 103-1 in the unit pixel 500-1 illustrated inFIG. 24C are formed in the lateral direction of the drawing. The slitson the light-blocking film 251-2 formed on the second opto-electronicconverter 103-2 in the unit pixel 500-2 are formed in a direction towardthe left and obliquely toward the lower side of the drawing.

The slits on the light-blocking film 251-5 formed on the secondopto-electronic converter 103-5 in the unit pixel 500-5 are formed in adirection toward the right and obliquely toward the lower side of thedrawing. The slits on the light-blocking film 251-6 formed on the secondopto-electronic converter 103-6 in the unit pixel 500-6 are formed inthe longitudinal direction of the drawing.

In the example illustrated in FIG. 24C, the slits are formed in the fourdirections. Similarly, in the other pixels (not illustrated), the slitsare formed on the light-blocking films 251 so that the slits are formedin four different directions in (two by two) four pixels depending onthe pixel. Note that, although the four directions are cited as anexample in this example, another direction can be added or, for example,the slits can be formed in two or three directions. The number ofdirections in which the slits are formed on the light-blocking films 251are not limited to four.

Forming the slits in different directions pixel by pixel as describedabove, in other words, varying the directions in which the slits areformed on the light-blocking films 251 formed on the adjacent secondopto-electronic converters 103 pixel by pixel can block the polarizedlight from different directions.

Additionally, when the direction in which the slits are formed variesdepending on the pixel as described above, for example, when the slitsare formed in different directions in the four pixels illustrated inFIG. 24C, respectively, the four unit pixels can have the same color. Inother words, the colors can be arranged in Bayer arrangement in whichthe four pixels have the same color as illustrated in FIG. 23B, and theslits can be formed in different directions in the four pixels havingthe same color, respectively.

<Exemplary Variation>

An example in which two opto-electronic converters with differentsensitivities are arranged in a pixel has been described above. However,three or more opto-electronic converters with different sensitivitiescan be arranged in a pixel. The difference of the sensitivities can beadjusted by changing the material or thickness of the light-blockingfilm.

Additionally, an example in which the present technology is applied to aCMOS image sensor having unit pixels arranged in rows and columns hasbeen described in the embodiments. However, the application of thepresent technology is not limited to the application to a CMOS imagesensor. In other words, the present technology can be applied to all ofimage pick-up apparatuses in which unit pixels are two-dimensionally inrows and columns in an X-Y address scheme.

Furthermore, the present technology can be applied not only to an imagepick-up apparatus that detects the distribution of visible incidentlights and captures the lights as an image but also to all the imagepick-up apparatuses that capture the distribution of incoming infraredrays, X-rays, or particles as an image.

Note that the image pick-up apparatus can be formed as a chip, or can beformed as a module having an image pick-up function in which an imagepick-up unit and a signal processing unit or an optical system arepackaged.

<Exemplary Usage of Image Pick-Up Apparatus>

FIG. 25 is a diagram of exemplary uses of the image pick-up apparatus.

The image pick-up apparatus can be used for various purposes in whichlights including visible lights, infrared rays, ultraviolet lights, or Xrays are sensed as described below.

-   -   An apparatus that captures an image for appreciation, such as a        digital camera, or a mobile phone with a camera function.    -   An apparatus used for traffic purposes, such an in-vehicle        sensor that captures an image of the view in front of, around,        behind, or in the car for safe driving including automatic stop        and recognition of the driver's condition, a monitoring camera        that monitors running vehicles, or roads, or a distance        measurement sensor that measures the distance between the        vehicle and another vehicle.    -   An apparatus used for home electrical appliances including a TV,        a refrigerator, and an air conditioner. The apparatus captures        an image of the user's gesture to control the appliance in        accordance with the gesture.    -   An apparatus used for medical care or health care, such as an        endoscope or a device that captures an image of vessels by        receiving infrared lights.    -   An apparatus used for security, such as a monitoring camera for        security or a camera used for personal verification.    -   An apparatus used for cosmetic purposes, such as a skin        condition measurement device that captures an image of skin, or        a microscope takes an image of the scalp.    -   An apparatus used for sport, such as an action camera or a        wearable camera for sports.    -   An apparatus used for agricultural purposes, such as a camera        that monitors fields and crops.

FIG. 26 is a block diagram of an exemplary configuration of an imagepick-up apparatus (camera device) 1001 that is an exemplary electronicdevice using the present technology.

As illustrated in FIG. 26, the image pick-up apparatus 1001 includes,for example, an optical system including a lens group 1011, an imagepick-up element 1012, a DSP 1013 that is a camera signal processingunit, a frame memory 1014, a display device 1015, a recording device1016, an operation system 1017, and a power-supply system 1018. The DSP1013, the frame memory 1014, the display device 1015, the recordingdevice 1016, the operation system 1017, and the power-supply system 1018are connected to each other via a bus line 1019.

The lens group 1011 captures the incident light (image light) from anobject and forms an image on the image pick-up surface of the imagepick-up element 1012. The image pick-up element 1012 converts the amountof incident light with which the lens group 1011 forms an image on theimage pick-up surface into electric signals pixel by pixel so as tooutput the electric signals as pixel signals.

The display device 1015 includes a panel display device such as a liquidcrystal display device or an organic electro luminescence (EL) displaydevice so as to display the video or still image captured by the imagepick-up element 1012. The recording device 1016 records the video orstill image captured by the image pick-up element 1012 onto a recordingmedium such as a memory card, a videotape, or a Digital Versatile Disk(DVD).

The operation system 1017 issues instructions for the operation ofvarious functions of the image pick-up apparatus 1001 under the controlby the user. The power-supply system 1018 properly supplies variouspower sources as the power sources of the operation of the DSP 1013, theframe memory 1014, the display device 1015, the recording device 1016,and the operation system 1017.

The image pick-up apparatus 1001 described above is applied to a videocamera, or a digital still camera, additionally, to a camera module fora mobile device such as a smartphone, or a mobile phone. The imagepick-up apparatus 1001 can use the image pick-up apparatus described ineach of the embodiments described above as the image pick-up element1012. This can improve the image quality of images captured by the imagepick-up apparatus 1001.

Herein, the system means the whole of an apparatus including a pluralityof devices.

Note that the effects described herein are merely examples. The effectsof the present technology are not limited to the described effects andcan include another effect.

Note that the embodiments of the present technology are not limited tothe embodiments described above and can variously be changed withoutdeparting from the gist of the present technology.

Note that the present technology can have the following configurations.

(1)

-   -   An image pick-up apparatus including:    -   a pixel array unit, a plurality of unit pixels being arranged in        the pixel array unit,    -   the unit pixel including    -   a first opto-electronic converter, and    -   a second opto-electronic converter having a sensitivity lower        than a sensitivity of the first opto-electronic converter,    -   the second opto-electronic converter including a light-blocking        film formed on a side of the second opto-electronic converter        from which light enters the second opto-electronic converter.

(2)

-   -   The image pick-up apparatus according to (1), wherein a lens        used to collect light entering the second opto-electronic        converter is not formed on the second opto-electronic converter.

(3)

-   -   The image pick-up apparatus according to (1) or (2), wherein a        light-blocking wall used to prevent light from leaking from an        opto-electronic converter into opto-electronic converters next        to the opto-electronic converter is provided between the        opto-electronic converters.

(4)

-   -   The image pick-up apparatus according to any of (1) to (3),        wherein the light-blocking film has a slit.

(5)

-   -   The image pick-up apparatus according to (4), wherein directions        in which slits are formed on light-blocking films formed on the        adjacent second opto-electronic converters are different.

(6)

-   -   The image pick-up apparatus according to any of (1) to (5),        being a backside-illumination image sensor.

(7)

-   -   The image pick-up apparatus according to any of (1) to (5),        being a frontside-illumination image sensor.

(8)

-   -   The image pick-up apparatus according to (7), wherein the        light-blocking film is formed on a lower or upper side of a        wiring layer formed on the second opto-electronic converter.

(9)

-   -   The image pick-up apparatus according to any of (1) to (8),        wherein the light-blocking film is an amorphous silicon film, a        polysilicon film, a Ge film, a GaN film, a CdTe film, a GaAs        film, an InP film, a CuInSe2 film, Cu2S, a CIGS film, a        non-conductive carbon film, a black resist film, an organic        opto-electronic conversion film, or a metal film.

(10)

-   -   An imaging device, comprising:    -   a substrate;    -   a first opto-electronic converter having a first area formed in        the substrate;    -   a second opto-electronic converter having a second area formed        in the substrate, wherein the first area is larger than the        second area;    -   a trench extending from a first surface of the substrate,        wherein at least a portion of the trench is between the first        opto-electronic converter and the second opto-electronic        converter.

(11)

-   -   The imaging device according to (10), wherein the first and        second areas are parallel to the first surface of the substrate.

(12)

-   -   The imaging device according to (10) or (11), wherein the first        and second areas correspond to light-receiving surfaces of the        first and second opto-electronic converters respectively.

(13)

-   -   The imaging device according to any of (10) to (12), wherein the        first opto-electronic converter has a higher sensitivity than        the second opto-electronic converter.

(14)

-   -   The imaging device according to any of (10) to (13), further        comprising a pixel separation region between the first and        second opto-electronic converters, wherein the trench is formed        in the pixel separation region.

(15)

-   -   The imaging device according to any of (10) to (14), wherein a        light-blocking wall is formed in the trench and includes an        insulating film extending from the first surface of the        substrate.

(16)

-   -   The imaging device according to any of (10) to (15), wherein a        light-blocking wall is formed in the trench, and wherein the        light-blocking wall includes at least one of a negative fixed        charge film, an oxide film, and a metal.

(17)

-   -   The imaging device according to any of (10) to (16), further        comprising a light-blocking film,    -   wherein the light-blocking film is formed over at least a        portion of the second area of the second opto-electronic        converter, wherein the light-blocking film absorbs a portion of        light incident on the imaging device.

(18)

-   -   The imaging device according to any of (10) to (17), wherein the        light-blocking film overlaps the trench.

(19)

-   -   The imaging device according to any of (10) to (18), wherein the        light-blocking film overlaps a portion of the first        opto-electronic converter.

(20)

-   -   The imaging device according to any of (10) to (19), further        comprising an on-chip lens formed over the first area of the        opto-electronic converter, wherein no on-chip lens is formed        over the second area of the second opto-electronic converter.

(21)

-   -   The imaging device according to any of (10) to (20), further        comprising a color filter, wherein the color filter extends        across at least a portion of the first area of the first        opto-electronic converter.

(22)

-   -   The imaging device according to any of (10) to (21), wherein the        color filter extends across the light-blocking film.

(23)

-   -   The imaging device according to any of (10) to (22), wherein the        light-blocking film includes a slit.

(24)

-   -   The imaging device according to any of (10) to (23), wherein the        light-blocking film forms a polarizer.

(25)

-   -   The imaging device according to any of (10) to (24) further        comprising a plurality of light-blocking walls, wherein the        first opto-electronic converter extends from a first        light-blocking wall to a second light-blocking wall to a third        light-blocking wall.

(26)

-   -   The imaging device according to any of (10) to (25) further        comprising a plurality of first opto-electronic converters,        wherein the first opto-electronic converters are disposed in a        plurality of rows and a plurality if columns;    -   a plurality of second opto-electronic converters, wherein the        second opto-electronic converters are disposed in a plurality of        rows and a plurality of columns, wherein a centerline of at        least one of the rows of the plurality of first opto-electronic        converters does not intersect any of the second optoelectronic        converters, wherein a centerline of at least one of the rows of        the plurality of second opto-electronic converters does not        intersect any of the first optoelectronic converters, and        wherein a line diagonal to at least one of the rows intersects        at least one of the first opto-electronic converters and at        least one of the second opto-electronic converters.

(27)

-   -   An imaging device, comprising:    -   a substrate;    -   a first opto-electronic converter;    -   a second opto-electronic converter having a sensitivity lower        than a sensitivity of the first opto-electronic converter;    -   a trench extending from a first surface of the substrate,        wherein at least a portion of the trench is between the first        opto-electronic converter and the second opto-electronic        converter.

(28)

-   -   An electronic apparatus, comprising:    -   an optical system;    -   an image pick-up element that receives light from the optical        system, the image pick-up element, including:    -   a substrate;    -   a first opto-electronic converter having a first area formed in        the substrate;    -   a second opto-electronic converter having a second area formed        in the substrate, wherein the first area is larger than the        second area;    -   a light-blocking wall extending from a first surface of the        substrate, wherein at least a portion of the light-blocking wall        is between the first opto-electronic converter and the second        opto-electronic converter;    -   a digital signal processor that processes signals received from        the image pick-up element.

(29)

-   -   The electronic apparatus according to (28), wherein the        electronic apparatus is included in a vehicle.

REFERENCE SIGNS LIST

-   -   10 CMOS image sensor    -   11 Pixel array unit    -   12 Vertical drive unit    -   13 Column processing unit    -   14 Horizontal drive unit    -   15 System control unit    -   16 Pixel drive line    -   17 Vertical signal line    -   18 Signal processing unit    -   19 Data storage unit    -   100 Unit pixel    -   101 First opto-electronic converter    -   102 First transfer gate unit    -   103 Second opto-electronic converter    -   104 Second transfer gate unit    -   105 Third transfer gate unit    -   106 Charge accumulation unit    -   107 Reset gate unit    -   108 FD unit    -   109 Amplification transistor    -   110 Selection transistor    -   151 Fourth transfer gate unit    -   203, 251, 303, 331, 351, and 381 Light-blocking film

The invention claimed is:
 1. An imaging device, comprising: a substrate;a first opto-electronic converter having a first area formed in thesubstrate; a second opto-electronic converter having a second areaformed in the substrate, wherein the first area is larger than thesecond area; a trench extending from a first surface of the substrate,wherein at least a portion of the trench is between the firstopto-electronic converter and the second opto-electronic converter; anda light-blocking film, wherein the light-blocking film is formed over atleast a portion of the second area of the second opto-electronicconverter, wherein the light-blocking film absorbs a portion of lightincident on the imaging device, and wherein the light-blocking filmincludes a slit.
 2. The imaging device of claim 1, wherein the first andsecond areas are parallel to the first surface of the substrate.
 3. Theimaging device of claim 1, wherein the first and second areas correspondto light-receiving surfaces of the first and second opto-electronicconverters respectively.
 4. The imaging device of claim 1, wherein thefirst opto-electronic converter has a higher sensitivity than the secondopto-electronic converter.
 5. The imaging device of claim 1, furthercomprising: a pixel separation region between the first and secondopto-electronic converters, wherein the trench is formed in the pixelseparation region.
 6. The imaging device of claim 1, wherein a lightblocking wall is formed in the trench and includes an insulating filmextending from the first surface of the substrate.
 7. The imaging deviceof claim 1, wherein a light blocking wall is formed in the trench, andwherein the light blocking wall includes at least one of a negativefixed charge film, an oxide film, and a metal.
 8. The imaging device ofclaim 1, wherein the light-blocking film overlaps the trench.
 9. Theimaging device of claim 1, wherein the light-blocking film overlaps aportion of the first opto-electronic converter.
 10. The imaging deviceof claim 9, further comprising: an on-chip lens formed over the firstarea of the first opto-electronic converter, wherein no on-chip lens isformed over the second area of the second opto-electronic converter. 11.The imaging device of claim 1, further comprising: a color filter,wherein the color filter extends across at least a portion of the firstarea of the first opto-electronic converter.
 12. The imaging device ofclaim 11, wherein the color filter extends across the light-blockingfilm.
 13. The imaging device of claim 1, wherein the light-blocking filmforms a polarizer.
 14. The imaging device of claim 1, furthercomprising: a plurality of light-blocking walls, wherein the firstopto-electronic converter extends from a first light blocking wall to asecond light-blocking wall, wherein the second opto-electronic converterextends from the second light-blocking wall to a third light blockingwall.
 15. The imaging device of claim 1, further comprising: a pluralityof first opto-electronic converters, wherein the first opto-electronicconverters are disposed in a plurality of rows and a plurality ofcolumns; a plurality of second opto-electronic converters, wherein thesecond opto-electronic converters are disposed in a plurality of rowsand a plurality of columns, wherein a centerline of at least one of therows of the plurality of first opto-electronic converters does notintersect any of the second optoelectronic converters, wherein acenterline of at least one of the rows of the plurality of secondopto-electronic converters does not intersect any of the firstoptoelectronic converters, and wherein a line diagonal to at least oneof the rows intersects at least one of the first opto-electronicconverters and at least one of the second opto-electronic converters.16. An imaging device, comprising: a substrate; a first opto-electronicconverter; a second opto-electronic converter having a sensitivity lowerthan a sensitivity of the first opto-electronic converter; a trenchextending from a first surface of the substrate, wherein at least aportion of the trench is between the first opto-electronic converter andthe second opto-electronic converter; and a light-blocking film, whereinthe light-blocking film is formed over at least a portion of an area ofthe second opto-electronic converter, wherein the light-blocking filmabsorbs a portion of light incident on the imaging device, and whereinthe light-blocking film includes a slit.
 17. An electronic apparatus,comprising: an optical system; an image pick-up element that receiveslight from the optical system, the image pick-up element, including: asubstrate; a first opto-electronic converter having a first area formedin the substrate; a second opto-electronic converter having a secondarea formed in the substrate, wherein the first area is larger than thesecond area; a light-blocking wall extending from a first surface of thesubstrate, wherein at least a portion of the light-blocking wall isbetween the first opto-electronic converter and the secondopto-electronic converter; and a light-blocking film, wherein thelight-blocking film is formed over at least a portion of the second areaof the second opto-electronic converter, wherein the light-blocking filmabsorbs a portion of light incident on the image pick-up element, andwherein the light-blocking film includes a slit; and a digital signalprocessor that processes signals received from the image pick-upelement.
 18. The electronic apparatus of claim 17, wherein theelectronic apparatus is included in a vehicle.